The invention relates to a method for producing a plurality of stacks of sheet material from an initial stack of larger sheets by transversely and longitudinally cutting the stack of larger sheets using a single cutting machine.
In practice, it is frequently necessary to further process stacks of relatively lager sheet-like materials, such as stacks of large, individually printed sheets of paper. The edges of these large, parallelepiped or rectangular block-shaped stacks (called “initial or starting stacks” when used in the present application) are cut to produce a rectangular edge-trimmed starting stack with defined edge lengths. As a rule, this trimming occurs prior to forming the partial stacks, hereinafter called the “finished stacks”, that constitute the final cut products. The larger initial stack that has been trimmed on all four edges or sides is called the edge-trimmed starting stack in the context of the present invention. This edge-trimmed starting stack is then cut multiple times in one direction, each step creating a smaller partial stack. If necessary, an intermediate cut like that described in EP 0 056 874 A2 can be made after each cut that divides the partial stack before the next utility cut is made. This intermediate cut ensures precise, aligned cutting without the risk of cutting into printed labels on the sheets, for instance. Any waste that occurs is disposed of with this intermediate step, as is described for instance in EP 0 056 874 A2. After the edge-trimmed starting stack has been cut in one direction to create a rectangular full stack, as it is known in the terminology used for the present invention, this full stack is rotated 90 degrees. Then, it is cut again, and with every cut, a plurality of partial stacks is produced for creating a full utility stack.
The edge-trimmed starting stack thus undergoes multiple transverse cuts and then multiple longitudinal cuts. It is also possible to perform the aforesaid intermediate cuts in addition to the cuts with the longitudinal cut that follows the transverse cut. The rectangular full stack, as it is known in the terminology used for the present invention, is created from a plurality of partial stacks at the end of the cutting process.
Heretofore, two cutting machines are used for the described cutting process in which the edge-trimmed starting stack is cut transversely and longitudinally. The cutting planes for these two cutting machines are arranged at a right angle to one another so that, after the edge-trimmed starting stack is cut by the first cutting machine, the full rectangular stack created from the various partial stacks is fed to the other cutting machine without being rotated. This cutting machine then cuts the full rectangular stack. This produces the full stack from the plurality of partial stacks. One such method is described in EP 0 242 762 A2, for instance.
Also already known in the art are processes for converting an edge-trimmed rectangular starting stack to a full stack created from a plurality of partial stacks by means of a single cutting machine using transverse and longitudinal cuts, as disclosed in EP 0 453 953 A 1. In that document, the edge-trimmed starting stack disposed on a rear table for the cutting machine is advanced to the cutting machine using a back gauge, and the trimmed starting stack is cut by the cutting blade to create the partial stacks. These partial stacks are advanced onto a front table of the cutting machine, and from there, onto a transport base that is positioned on a table arranged to one side of the cutting machine. The partial stacks are rotated from the transverse orientation to the longitudinal orientation, and then moved either onto the transport base, together with the transport base, or after being removed from the transport base. Once the partial stacks have been removed from the transport base, they are placed on a rear table, creating an aligned rectangular full stack, and are advanced using the back gauge. Now, the full stack is separated into the plurality of partial stacks.
This method has a number of different disadvantages. One significant disadvantage is that the material remains on the transport base between the transverse cutting and the longitudinal cutting. This means that the transport base, which has a large surface area, must be moved. In addition, the transport base requires a table surface large enough to accommodate it. This makes it necessary for there to be sufficient space around the cutting machine to guide the transport base around the cutting machine. The transport base requires that it must always be possible to handle a stack arrangement that is essentially equivalent in size to full stack. Thus universal handling is not possible for a series of stacks, and it is not possible to handle a small format unit.
DE 195 15 705 C1 and EP 0 091 714 A 1 describe additional methods for producing utility stacks by transversely and longitudinally cutting rectangular starting stacks made of a plurality of sheets. However, this prior art uses three cutting machines.
EP 1 018 408 A 1 describes a method for cutting stacked, sheet-like material in which a cutting machine and a mobile alignment station that can be connected to it are used for partial stacks that are created during cutting. The mobile alignment station is not used until the starting stack that is present after edge trimming is divided into partial stacks in the one direction and these partial stacks are rotated 90 degrees, so they can then be cut into small partial stacks. The mobile alignment station is connected to the cutting machine in the area of the front table part, so that a straight edge on the mobile alignment station can assume the alignment function and support the partial stacks when they are cut. The cut partial stacks are then removed through a transverse channel formed between the straight edge and another straight edge. This is accomplished by an ejector tool.